JPL scientists celebrate 10 years of Cassini

This false-color mosaic from NASA's Cassini spacecraft shows the tail of Saturn's huge northern storm in June 2011. JPL scientists celebrated 10 years of Cassini spacecraft this week.

This false-color mosaic from NASA's Cassini spacecraft shows the tail of Saturn's huge northern storm in June 2011. JPL scientists celebrated 10 years of Cassini spacecraft this week. (NASA/JPL-Caltech/Space Science)

Sara Cardine, sara.cardine@latimes.com

On June 30, 2004, scientists and engineers at JPL held their breaths as 800 million miles from Earth, the Cassini spacecraft succumbed to the pull of Saturn's gravity field.

After seven years in transit, the craft was set to begin a four-year mission orbiting around the ringed planet for the purpose of learning more about its composition, satellite moons and particular rings.

Today, 10 years and two mission extensions later, Cassini is still circling the outer planet, returning valuable data that could shape the future of solar-system science. The people who negotiate its propulsion, direct its actions and collect and analyze its findings say the craft is still in good shape and will make it until 2017.

"The scientific bang for the buck has been unbelievable," said Todd Barber, a lead engineer for flight operations who's worked on the mission since 1997. "Cassini is a marathon, and we're going to be rewriting the texts on outer planetary science for decades."

JPL will mark Cassini's 10-year anniversary Thursday in a private event. The celebration is sure to be tinged with a little nostalgia as those involved in the mission contemplate its 2017 end date, which will culminate with a "Grand Finale" phase.

During this phase, running on the very last of its engine propellant, the craft will make an improbable journey in between Saturn's rings and its surface, explained David Doody, lead engineer for real-time flight operations.

For 22 orbits, Cassini will be closer than ever before to the planet itself, close enough for it to detect data about its composition through the icy ammonia clouds that form its atmosphere. When that cycle has ended, Cassini will dive into the planet, eventually yielding to intense heat and pressure.

This technological suicide is done to spare whatever microbial life may exist on Titan and Enceladus or other Saturnian moons, Doody explained.

"We wouldn't want to land on Enceladus or Titan inadvertently, so we're just going to burn it up in Saturn's atmosphere," he said.

Upon its death, Cassini will have orbited Saturn for 13 years, enough to have allowed it to witness nearly half a Saturnian year, the equivalent of 29.7 Earth years. It will have dived through mysterious ice plumes spewing out of Enceladus' inner ocean and inspired more than 3,000 scientific reports.

But for Barber and Doody, the legacy of Cassini will have been even greater.

"We might look back and realize this mission opened up our thoughts about what it takes to find a habitable place in the solar system," Barber said, explaining the ingredients for life present on Saturn's moons. "I bet we'll be remembered for that."

--FOR THE RECORD: An earlier version of this story incorrectly named Todd Barber as Todd Parker.